Circuit module chassis assemblies which include multiple circuit modules mounted in a chassis are widely used in electronic applications. A circuit module chassis assembly may include a chassis configured to mechanically support the circuit modules, electrical connectors to interconnect the circuit modules, power supplies for operation of the circuit modules and one or more external connectors to connect the circuit module assembly to external equipment. The circuit module chassis assemblies are widely used in military and aircraft applications, but are not limited to such applications. Circuit module chassis assemblies for military applications must be designed to operate reliably in harsh environments.
The circuit module chassis assemblies typically require a cooling system to remove heat generated by the circuit components and to maintain the circuit modules within a specified temperature range. Various cooling techniques are utilized, including conduction cooling, air-flow-through cooling and liquid-flow-through cooling. By way of example, conduction cooling may be used up to 70 watts heat generation, air-flow-through cooling may be used up to 250 watts heat generation, and liquid-flow-through cooling may be used up to 1000 watts heat generation. The trend is toward circuit modules which have higher speed and higher performance, but which generate larger amounts of heat.
A problem arises in that the three cooling approaches are incompatible in the circuit module chassis assembly. Conduction-cooled circuit modules typically conduct heat to the sidewalls of the chassis, and the side walls are provided with heat exchanger fins for heat dissipation. By contrast, air-flow-through and liquid-flow-through chasses do not have heat exchangers in the sidewalls. Instead, the sidewalls of the chassis are used for coolant distribution. Accordingly, a conduction-cooled circuit module previously could not be mounted in a chassis that is designed for air-flow-through cooling or liquid-flow-through cooling. The chassis could be designed to have a conduction-cooled section and an air-cooled or liquid-cooled section. However, this approach limits the application of the chassis to a fixed number of conduction-cooled circuit modules and a fixed number of air-cooled or liquid-cooled circuit modules, thereby reducing the flexibility of the design.
Accordingly, there is a need for cooling assemblies which permit conduction-cooled circuit modules to be utilized in chasses that are designed for air-flow-through or liquid-flow-through cooling.